Embodiments of the invention may be implemented in any network in which labels are used for routing of data packets within a network. One example of such a network is a multi protocol label switching (MPLS) network.
As will be known by the skilled person, in a MPLS network the data payload to be carried by the MPLS network is provided with a header containing one or more labels. The labels define a label switched path (LSP) that determines the network node to which the data packet is to be forwarded as the data packet travels through the MPLS network.
At an edge node of the MPLS, therefore, one or more labels are added to the received data payload, and the resulting data packet is forwarded to an intermediate network node using the label switched path (LSP) defined by the label. At the intermediate node, the label is swapped or replaced with a label that is meaningful for the next label switched path (LSP) to the next MPLS network node. Each network node is provisioned with labels for the outgoing label switched paths from that network node. A sequence of label switched paths (LSP) form a Label Switched Path Tunnel (LSP tunnel), which defines a pathway between successive network nodes through the MPLS network along which successive packets can be sent.
Congestion within a data network can cause deterioration in the overall performance of the network. One way in which congestion may be managed is by determining on a packet by packet basis whether a data packet is eligible to be discarded, i.e. not forwarded onwards within the network. Typically discard eligibility may be determined for a packet as it enters the MPLS network at an edge node, based on the service agreement relating to the packet and network congestion information.
Typically discard eligible information (DEI) is included in the data packet at the MPLS edge node depending on the discard eligibility. Subsequently, when the data packet is received at a network node, the discard eligible information (DEI) can be used to determine the discard eligibility of the packet. If the data packet is discard eligible, a determination whether to discard the packet can be made depending on the local congestion information.
An exemplary form of discard eligibility is the service disposition defined in Metro Ethernet Forum (MEF) standard MEF10 as follows:
ServiceAction atdispositionedge nodeAction at intermediate nodeRedDiscardnone necessaryYellowadd DEI toDeliver according to the Service Attributes ofpacketthe service instance but service level (SLS)performance objectives do not apply.Greenadd DEI toDeliver according to the Service Attributes ofpacketthe service instance and service level (SLS)performance objectives apply.
Data packets having different quality of service requirements may be carried on the same label switched path by defining different classes of service. In particular, a Label Switched Path (LSP) can be used to support one or more ordered aggregates. Such label switched paths can support up to eight behaviour aggregates of a given forward equivalency class regardless of how many ordered aggregates these behaviour aggregates span.
It is envisaged that in the future the demand for network capacity to handle data packets having differentiated classes of service, together with discard eligible information (DEI) will increase.
The present invention seeks to alleviate or ameliorate at least some of the disadvantages of the prior art, and to provide a novel method and a device for creating a data packet with discard eligible information and a novel method and device for receiving a data packet with discard eligible information.